What a stunning read this is. Hat-tip to Steph for finding it. It explains how a company, called Cambridge Analytica, are using pyschometrics to profile and target millions of people around the world (based on personal data that’s been accrued directly or indirectly through profiling). A choice quote:

on the map, there are hundreds of thousands of small red and blue dots. Nix narrows down the criteria: “Republicans”—the blue dots disappear; “not yet convinced”—more dots disappear; “male”, and so on. Finally, only one name remains, including age, address, interests, personality and political inclination.